Carbon black process



May l5, 1945. 1. c. KREJCI CARBON BLACK PROCESS Filed Deo. 22, 1941 Infu INVENTOR JOSEPH C. KREJCI A'l'l'gNEY Patented ttlay l5, i945 tossesc. areal, naw, ons., a signor t@ remisslletroleum Company, a corporationof Dela- .application December 22, 1941, Serial No. 424,084

8 Claims.

This invention relates to a process for producing carbon black, and moreparticularly it relates to amethod for producing carbon black by theincomplete combustion of carbonaceous gases and vapors or bydecomposition thereof by Contact with hot gases.

Attention is directed to copending applications Ser. No. 431,171, filedFebruary 16, 1942; Ser. No. 436,524, filed March 27, 1942; Ser. No.445,338, led June 1, 1942; and Ser. No. 469,016, led December 14, 1942,wherein related subject matter is disclosed.

At the present time, most of the carbon blacks of commerce are producedby a very few processes and these blacks may be grouped into classesdepending upon the types of rubber compound and vulcanized rubber whichthe carbon blacks will produce. A soft carbon black as compared to ahard carbon black is one which when mixed in a conventional rubbercompound and then vulcanzed yields a product which is softer, moreresilient, more rubber-y and yet tough whereas a hard carbon black inthe same compound imparts stiffer, tougher characteristics, with lowerresilience.

-carbon than the channel process, but in essentially all cases theseblacks are of a softer type and less desirable for use in good qualitytire tread stocks. These latter blacks, however, nnd other and varieduses, which are minor as compared to the relatively large amounts ofhard channel black which go into tires at the present time and a processwhich would give a high yield of a hard black similar to channel blackin properties, would be most desirable.

The principal object of this invention is to provide an apparatus and aprocess for producing carbon black oi high yield and of qualitycomparable to or superior to the present day channel black for use intire stocks.

Another object of this invention is to improve on the present day art ofproducing carbon black by providing an apparatus and a process whichwill produce carbon black out of contact with solid surfaces withoutdepending on maintenance of streamline now conditions as in some otherprocesses, and with an extremely short reaction time.

Still another object of this invention is to provide a carbon blackmaking process which is ilexible in operation and especially in therespect that a product of essentially any desired properties rangingfrom those of the conventional soft car bon blacks, through theintermediate blacks, to the hard channel blacks, or even harder, can beproduced with the same apparatus and raw materials merely by alterationand control of the operating conditions.

Still other objects and advantages will be apparent to those skilled inthe art from a careful study of the following description anddisclosure:

The accompanying diagrammatic drawing is a part of this specication andillustrates preferred forms of the apparatus for carrying out myinvention, in which:

Figure 1 is a longitudinal section of a preferred form of the reactionchamber along the line l-l of Figure 2;

Figure 2 is across sectional view of the preferred form of the reactionchamber along the line 2--2 of Figure 1;

Figure 3 is a part longitudinal elevation and part longitudinal sectionof another embodiment of my reaction chamber, the longitudinal sectionbeing taken along the line 3-3 of Figure 4;

Figure 4 is a cross sectional view of this latter embodiment of myreaction vchamber along the line '--d oi Figure 3.

Like numerals on the several figures refer to the same or similar parts.This drawing has been presented in diagrammatic form only, and suchconventional and well known parts as valves, flow meters, pressureregulators, temperature measuring devices, etc., foi` simplicity havenot been shown.

Referring to the figures, the cylindrical reaction chamber I has alining i I of highly refractory material such as sillimante or alundum.Between this refractory liner II and the cylindrical steel shell I3 is alayer of insulation I2. The ratio of the length to the diameter of thechamber has not been found to be critical, ratios ranging from 2 to 10have been found to give good results. The chamber is equipped with afuel burner I extending through the chamber wall and terminating in anoval-shaped opening such that the incoming gaseous mixture enters thereaction chamber tangential to the inside cylindrical surface of thechamber and perpendicular to the longitudinal axis thereof. Thetemperature within the chamber may be measured through one or moreopenings, as 20. At the inlet end, the chamber is equipped with inlettube I 6 which is in line with the longitudinal axis. If one gas only isadmitted to the inlet end of the chamber, this tube I6 extends throughthe refractory, insulation and shell, but in case a mixture of two gasesis admitted, a Y I9 is used, one of the gases being introduced througharm I1 and the other through arm I8 with tube I6 in this case serving asa mixing tube as well as the chamber inlet tube. Tubes 2I from thepreheat furnace carrying the reactant gas and air are connected tothe Yas shown in Figures i and 3.

Figures 3 and 4 illustrate the reaction chamber in the main as in Figure1, but with some modifications which IA have found advantageous. The useof two or three additional tangential burners I5, as in Figure 3,permits a more nearly uniform distribution of heat throughout the lengthof the chamber, and in addition reduces by as much as 30% the total fuelrequired to keep the chamber walls free of carbon. When two Or moretangential burners I5 are used it is not necessary that they be equal Insize, since it has been found advantageous to introduce most of the fuelthrough a larger burner I5 at the inlet end of the chamber and to useseveral small burners throughout the length of the chamber as an aid inpreventing carbon deposition. In this way the reactant gas comes intocontact with a greater portion of the fuel throughout the length of thechamber.

In the apparatus embodiment shown in Figure 3, a modification of thechambers cross section by insertion of conical shape 22 has been foundvaluable as a means of regulating the extent of mixing between thereactant gas and the tangential burner flame to any desired degree.

The introduction of air tangentially into the annular space 23 aroundmixing inlet tube I6 by means of tube 24. as in the chamber modificationshown in Figure 3, has been found suitable as a means for the preventionof carbon deposition on the back wall 25. Due to the centrifugal forceimparted by the tangential motion, the air spreads out on emerging fromthe annular space 23 and blankets the back wall of the chamber thuskeeping the reactant gas out of contact with the wall. The mixing tubeI6 and the annular duct or space 23 were extended into the chamber forconvenience in installation of air tube 24, The annular space 26surrounding the back wall 25 may be filled-with a refractory material,if desired.

The reaction or chamber products exit from the open end of the reactionchamber, and are immediately cooled. Applicant has found that a spray ofwater absorbs sufficient heat to cool said products sufficiently belowthe temperature at which the carbon black particles continue to grow. Awater spray I is shown diagrammatically in Figures 1 and 3.

In the carrying out, or operating, according to my invention, a mixtureof fuel such as natural gas and air is introduced through tangentialburner or burners I5 at sufficient velocity to cause the iiame to adhereto the inside surface of the chamber and form a blanket of ilame andproducts of combustion over the chamber wall throughout its length.Velocities of the incoming gaseous mixture through the tangential burnerports may vary over wide limits, but must necessarily be rather high lncase the gaseous fuel and air are mixed in explosive proportions. Inthis case, the rate of flow of this fuel must be faster than the linearrate of flame propagation in said fuel mixture to prevent an explosion.Applicant has found that this velocity of tangential gas flow may varyfrom as low as 30 feet per second orless to 200 feet per second, or evenmore, In one test, best results 'were obtained by maintaining this fuelgas velocity within the range of 1GO to 150 feet per second. When airalone is used as the tangential gas, carbon is easily prevented fromdepositing on the chamber walls'even at very low tangential velocities.Thus it is seen that the tangential gas may vary between wide limits ofcomposition, ranging from air alone on the one hand to the theoreticalmixture of combustible gas and air on the other hand, or even richerthan the theoretical mixture provided the mixture is not so rich as topermit carbon deposition on the chamber side walls.

The tangential fuel velocity should be rather high to maintain bycentrifugal force a layer or blanket of flame and combustion products onthe inside of the chamber wall. The tangential ame and combustionproducts travel from the tangential burner inlet toward the outlet endof the reaction chamber I0 following helical path adjacent the insidewall of said reaction chamber thereby forming essentially a continuouslayer or blanket of flame and combustion products on said inside wall.'I'his layer or blanket of name serves as a separating medium to preventcontact of the central contents of the chamber and the side walls.

A carbon bearing gas such as natural gas or a mixture of such gas andair with less than sufficient air for complete combustion is introducedinto the reaction chamber Ill through tube I6. The carbon bearing gasand the oxygen bearing gas passed through the said inlet tube IB will behereinafter referred to as reactant gas and reactant air, respectively.If reactant air is not mixed with the incoming reactant gas at thispoint for furnishing endothermic heat to the reactants after they enterthe reaction chamber, said heat of reaction is then supplied by thetangential flame. The tube I6 directs the reactants along thelongitudinal axis of the chamber and this in addition to the effect ofthe tangential flame which keeps the reactant gas away from the walls ofthe chamber assures that the reaction to carbon takes place in thecentral core of the chamber. In operations when oxygen containing gas ismixed with the reactant gas and tube I6 serves as the mixer, it shouldbe suiilciently large to mix them effectively xfacturing carbon blackfrom natura-l gas conraining 35 pounds of carbon per 1000 cubic feet.vhen using my appaartus and according to my Jrocess.

In the above runs, B611?. and B46R, the amount 3f fuel used in thetangential burner was not sulcent to keep the chamber wall free ofcaroon. Reactant gas and reactant air were heated ndividually in thepreheat furnace and to the same temperature. as recorded in the secondcolumn of Table I. In all tests or runs excepting run B99, the gas andair to the tangential burner were `not preheated, that is, the fuelmixture entered the said burner at atmospheric temperature. [n run B99,however, the air portion of the tangential fuel'was preheated to 200G l.It might be mentioned, also, that while it is not necessary, thetangential burner fuel was composed of air and gas in the theoreticalratio for complete com bastion to carbon dioxide and water.

It should he noted from the above data that the carbon black yields areexceptionally high, and especially so when considering the 3.5% yield ofthe commercial channel process when treating a natural gas of 35 poundcarbon content. It might be noted, also, that the higher yields of blackwere obtained when the reactant gases contained no air or as termedabove. no reactant air. From the above data, it seems that thelessreactant air used with a given amount of reactant gas, the higherthe carbon black yield. In addition, a relation also seems to existbetween the amount of combined tangential air and gas and the carbonblack yield.

Carbon black has been made by commercial processes with yields as highas o1 the @an hon content of the gas. but in :auch cases, the carbonblack did not have the reinforcing proporties of channel black. In fact,such black is very inferior for rubber tire making purposes to the lowyield channel black and therefore found only a limited market for otherpurposes.

One of the outstanding advantages of my process lies in the fact thatethough the yield is high, a hlaclf. can be produced oi' a qualitysatisfactory for tire tread purposes and in some properties superior toconventional channel black. The channel black of conirnerce is used,herein as a standard or' tire tread stoclc quality since black made bythat process is acceptable to the tire manufacturers. To illustrate thequality ci" the carbon black. made as herein disc .ed and to compare itsproperties with those o channel black, batches of rubber compound wereprepared according to the compounding formula, as follows:

Parts by weight Smoke sheet 100 Carbon black: 50 Zinc oxide 5 Stearicacid 3 Phenyl nsphthylamine- 1 Captax 0.9 Pine tar i- 3 AllVulcanlzations were made at 274 F. for variable lengths of time as setforth in Table I below. The test pieces for the resilience tests. asmeasured with a Yerzley oscillograph, were vulcanized for minutes at27e" v Toole n" Modulos,

. Acciona exstracpmms. f 5- Bfenk, met@ m sample 274 F pounds per tion.por 'jr ccm original can mmute' square in. cent l" bOD bllfli.

200% 500% per cent 20 520 2,660 4,000 30 690 3, lfi() 3, 900 i0 990 6603, 82() 90 1, 100 1i, 730

30 400 2, 210 4. 130 60 G10 2, 800 Il, 8940 90 610 2, 900 3, 650

w 500 2. 640 4. 60 710 3, 260 1i, l0() 90 770 3, 550 3, 870

30 600 3, 000 l, 4S() 60 840 3, 770 4, 270 l so 92o 4.120 4,190

30 490 2, 510 4,030 B99... 60 710 3,120 3,810 B99 JO 790' 3,310 3,730Channel bleek:

Hard black 30 460 2, 350 4, 110 Do. 60 760 3,19() 4, 270 D0 90 950 3.5&0 4, 250 Furnace black:

`0ft black 30 630 2,680 3,450 Do,... 60 870 2, 970 3, 230 D0 90 910 2,970

Table m, below, shows additional rubber tests using carbon black madeaccording to my process and in my apparatus. These results diner fromthose of Table Il in that the vulcanizatlons were made at 260 F., forthe times indicated. The resilience test samples were also vulcanized at260 F., and for a -perlod of 'l0 minutes. The resilience values as givenfor samples contain ing my carbon blaclr and vulcanized at 260 F..

classification, it is obvious that some samples in which applicantscarbon black is incorporated are similar to the hard channel black inproper ties, some are similar to the soft furnace black, while somepossess properties intermediate these two commercial types of black. A.point of importance is that some of applicants samples are harder inrespect to the physical properties of the rubber than the 'hard Channelblack sample.

are essentially the sanne for those vulcanized l `This point wouldindicate that tire tread stocks at al# F. compounded with certain ofapplicant's carbon Table I!! Modulos, Acciona ex Vulceulzapounds por sq.t o u r .tion et inch Bn'lk' Moana Resilience, hmmm on sample 2mg FPC'UBUS L! 1011, Der ar cfm original cermuj square n. cent p bon bleek,

296% 500% per cent so 56o 2, 75o 4, 30o 60 760 3, 490 4, 150 90 1, 0003, 790 4, 095

.'30 585 2, 880 4, 270 l) 810 3, 500 4, 07 5 90 l, 0l() 3, B00 4, 000

in Tables lil and lll, by the word vulcanication". heading the secondcolumn, is meant the length of time that the compound containing smokedsheet, carbon. blaclcy etc., is heated at the vulcaniaatlon temperature;in'Table E, the vulcanizing temperature is 274 F. and in Table Ill it is260" F., and the time is recorded in minutes. The 200% modulus columnrefers to the pounds per square linch pull in a tension test when thetest piece of vulcanized rubber has been stretched 200% oi the length ofthe original test piece; the 500% modulus" refers to the pounds persquare inch pull in a similar tension test when the test piece has beenstretched 500% of its original length. The Break column represents thepounds per square inch pull at the point of rupture or break of the testpiece undergoing the above mentioned 200% and 500% modulus tests.

blacks would yield better wearing and less easily abraded tires than theconventionalhlgh quality tires in which channel black is used. It willbe noted, also, that applicants carbon black; causes e0 the compound tovulcenize more rapidly than The elongation column represents the stretchor elongation at the point of break The resilience is the complement ofhysteresis loss, or more simply expressed is a, measure of the potentialenergy of e. piece ci rubber that; is present as a result of appliedstress and which is recoverable when the stress is removed. The acetoneextractoble is the per cent loss in weight of the original carbon blackupon extraction with acetone.

In addition to the tests on rubbers made with my carbon black, samplescontaining hard and soit blacks made by the Channel and Furnaceprocesses, respectively, are included in Table Il. and a Furnace black(soft black) in Table III for comparison.

Upon consideration of the data of Table Il, the modulus, break,elongation and resilience values of the channel black sample arecharacteristic of a "hard black. Similarly, the data pertaining to thefurnace black sample are characterlstic of a soft black. Based upon thisthe channel blaclt, and for this reason, it appears that applicantssamples which were vulcanized for 60 and 90 minutes had reached a stateof vulcanization more advanced than the regular control channel blacksamples. ln one case, that of the B57 sample of `carbon black or' TableIl, a 20 minutel vulcanization was made which yielded a good rubber inall respects, even superior in most respects to the channel black samplevulcanized for thirty minutes for tire tread 'purposes. literature andfamiliar to those vskilled in the art was the method used to determinethe extent of vulcanization. High resilience values arecharacteristically imparted to rubber by the soft urnace blacks. Thehigher resilience values among blacks of commerce ordinarily gohand-in-hand with the lower modulus values, for example, the furnaceblacks of Tables II and III, and vice versa, low resilience valuesordinarily accompany high modulus values, as for example, the channelblack of Table Il. One of the outstanding properties of applicantsblacks is their ability to iinpart to vulcanized rubber high modulusvalues and at the same time high resilience values. This property isextraordinary, as will be appreciated by those skilled in the art ofrubber compounding.

Considering the data of Table III, it may be seen that the samplesvulcanized at 260 F., and having my carbon black incorporated thereinpossess very excellent properties for tire tread stocks when compared tothe channel black sample of Table II. This data also indicates that myThe zero set test as described in the' to square.

`ber compounds, and that these rubbers nossess high modulus values alongwith high resilience.

Upon consideration of the data of Tables l1 and III, it is seen thatcertain of my carbon blacks are adaptable for making the type of rubberordinarily requiring a soft black, the type of rubber requiring hardblacks. and the type requiring intermediate blacks. These several typesof carbon blacks were made in my apparatus and according to my processby certain and syste matic variations of the operating conditions. Oneparticular' advantage of my process is that it is not limited to themaking of one particular kind or type of carbon blaclc, as are presentday commercial processes, but contrast is adaptable tc the making; of nureus types or kinds of carbon blecles, and these kinds ci carbon blackmay then be made to fit changing market, supply and demand conditions.in addition, another importent advantage of my process is the very highyield of carbon black obtained which high yield is e. definite stepforward in the conservation of a natural resource.

.en example in which pure methane was used as charge 'stock to myreaction chamber yielded 3 .to 5 pounds of carbon black per 1000 cubicfeet of methane. The 3 pound yield calculated to 9.5% yield per 100Dcubic feet of reactant methane. The 5 pound yield amounts to 15.8% ofthe available carbon. The 3 pound yield carbon was, however, somewhatsuperior in rubber making qualities to the 5 pound carbon.

In contrast, the channel process operating on pure methane, es in theabove experiment, gave only 9.75 pound carbon' or about 2.4% yield peri000 cubic feet of methane.

In another example, residue natural gas from a gasoline extractionplant, and a gas oil were used as charge stock. The residue natural gaswas heated to approximately 2000 F. in a preheater not shown in thedrawing and a gas oil of about 18 A. P. I. gravity added dropwise or ina relatively small stream to this'preheated gas during its passage fromthe preheater to the reaction chamber it. The gas oil was vaporized 'bythe high temperature residue gas and this gas-vapor mixture was chargedinto the reaction chamber as reactant gas alone or mixed with reactantair. Residue gas, as above, and air were entered into the chamber' lothrough the tan. gential burners l5. By control of this operation,

I as heretofore disclosed. a very high yield of ca bon black wasobtained. From the total yield of blacls was subtracted the yield due tothe residue gas, and the remainder of the blaclr calculated to 5 poundsblack per gallon of gas oil. This coinbined blacl: yielded rubber ciexcellent quality when made up and vulcanized as heretofore set forth.

Relating to the apparatus or more particularly to the reaction chamberi0 as shown in the drawing, it is not intended to limit the chamber tothe particular design es shown. The shape does not necessarily need tobe cylindrical, but may bernore oval in section or even rectangular Thetangential burners, in the case of small chambers, may be limited toone,l or in larger chambers may be two or more.'the'number depending onthev size of the chamber. When several burners are used, they can bedistributed along the length of the chamber as shown in Figures 3 andIl, or they can -be at the inlet end distributed around thecircumference of the chamber. In this latter case, it may be desirableto give the fuel some velocity downstream with Lilli asvavec respect tcthe chamber by directing the burners at a slightly less angle than flilto the longitw dinal axis of the chamber. The burner ports can be of anyshape such as round, oval or rectangular. A rectangular burner has anadvantage over a round one in that a greater portion of the fuel streamenters tangenti-ally with respect to the inside surface of the chamber,this being true in the ci" burners Wfl` cross sections having a largeratio of length width and with the longer dimension of the cross sectionparallel to the 1ongitudinal axis of the chamber. In one embodlment, alarge number of tangential openings may be provided in the lining of thechamber and supplied with fuel from annular space sur rounding thelining. in another' embodiment, a single rectangular rburr extendingthroughout the length of the che er can used.

The products issuing from the chamber t6 can be cooled by anyconventional means, such as mixing with a cool inert gas such asnitrogen, or with a spray of water. The position of the point ofintroduction ofthe cooling gases or water spray depends on the desiredtime of exposure of the carbon product to the hot gaseous products vofcombustion from the tangential flame. If a separate quenching chamber isprovided for each reaction chamber, it should preferably have about thesame diameter as the chamber and have its axis in line with the axis cithe reaction chamber. This arrangement permits the tangential Iflame tocontinue into the quenching chamber to alone.

v As disclosed heretofore lted to the use c neA .i the carbon containing gas, while in on to either dry gas, Wet gas or raw ges as itcomes from the well, or gasoline extraction plant or refinery residuegas, heavier' hydrocarbons such butano, or still heavier hydrocarbonproducts or fractions or even normally liquid hydrocarbons may be used,as for example, the gas oil previously disclosed. Oils heavier than theges oil of commerce may be used as a source or es. on well as lighteroils. suc'h as the kerosene i,- cticn, heavy or light naphthas, oneventhe gasoline range of hydro carbone. In addition, such ma ri ...s es lowtcm-- perature coal gas. coal ter distili es and oil shale gases anddistillates may bc used charge stoel: to my process.

The air or gas, or both, in the fuel to the tangential burners can hepreheated es moans oi introducing more heat into thc chamber. Fuel richin air, or air alone, preferably preheated, can be used in any or all ofthe tangential burn ers. Enriching the said fuel with air was found toreduce the fuel rate required to keep the charnber Wells free of carbon.When air alone is used in the tangential burners, the product has a grayish color ln comparison to the very black channel product, but the yieldo carbon black is high. As desired, the fuel mixture to the tangentialburners may be allowed to burn within the chamber or in a separatecombustion chamber, the hot combustion gases then being conductedtengentially into said chamber. Since the functions of the tangentialgases are to furnish heat to the chamber walls and to prevent depositionof carbon thereon, it is immaterial at what point the com bustion tairesplace, as long us the gases reach nrocess is not lim the cooling systemat which the products arev cooled to a temperature below which nofurther the chamber walls in a properly heated condition.

@ne advantage of my process over the prior art. lies in the fact that itmakes possible the rapid conversion of hydrocarbons -to carbon black outof contact with solidl surfaces in extremely short reaction times andwithout depending lon maintenance of streamline iiow. I have verifiedthat even under turbulent now ,conditionsa tangential layer of .gas canbe maintained to separate the wall and the gas occupying the centralcore of alcylindiical reaction chamber. The presence of a tangential'gaseous layer may be readily demonstrated by producing a yellow flamein the central core and then introducing air through one or moretangential ports when a, clear layer of air adjacent to the wall isvisible. Il'he thickness of this layer changes only little even if theamount of air introduced is two or three times the minimum required toestablish the clear layer. This additional air over the minimum isapparently mixed with the reactant gas in the central core, and thisfact is evidenced by the shortening of the yellow flame. If the air isintroduced axially as a uniform layer next to the vwall with astreamline flow in both the central flame and the air layer, a longdiffusion flame results but a clear layer of air is maintained betweenthe name and the Wall. However, as vthe velocities are increased intothe turbulent flow range, the name becomes shorter, the clear layeraddacent to the chamber Walls disappears, and the dame is then in directcontact with the wall and carbon may be deposited thereon.

In my process, the operation at sufficiently high linear velocityofreactant gas as to give turbulent flow results in rapid transfer of heatinto the moving body of reactant gas and decreases the time of reaction.AThis decreased time of reaction operates advantageously in my processsince a much greater output of carbon black per chamber results, and arelatively large output of black per unit of chamber volume ischaracteristic of my reaction chamber and process of operation.

Operatingunder said turbulent flow conditions in the reactant gas streamhas the advantage oi making any given cross section of the stream normalto the direction of :dow more nearly homogeneous with respect to stateso'f decomposition, combustion, and dilution. In contrast, a diffusionname, .characteristicv of other carbon black making processes, is likelyto have much tar and unreacted gas in the center, a surrounding layer ofsubstantially decomposed gas carrying goed quality carbon, and an outerlayer of completely decomposed gas carrying overheate'd carbon.

When premixed fuel is used in the tangential burners, surface combustionon the chamber walls ,takesl place thereby heating the walls to a veryhigh temperature. These heated walls then heat the reactant gases byradiation. An appreciable part of this surface combustion goes to CO2and H2O and does not revert to CO and I- lz because the carbon formingreactants do not mix completely with'the combustion products and becausethe time ature is tooshort.

The tangential name also has the function of diluting the products,particularly in the-latter part of the chamber. This dilution decreasesthe concentration of any undecomposed hydrocarbons and thus lessons thechance for carbon particle at elevated tempergrowth between the chamberand the point in,

reaction is .-possible.

4 Mixing of the reactant gas and the tangential ame within the chamberitself has been found to play an important role in my process. Inaddition to aiding in heat transfer, such mixing improves the quality ofthe product, as for example. the amount of acetone extractable' matterin the carbon black is readily controlled by regulating the extent ofthis mixing, the` greater the extent of mixing the less theacetoneextractable.

Another advantage of this process over the prior art is its greaterflexibility as to controlling the operation and as to control of thequality of product. The properties of the product can be varied over awide range by adjusting the fuel rate tothe tangential burner,V theratio of reactant air to reactant gas, gas and air preheat tempertures,reaction chamber temperature, and cooling of the chamber product, etc.Using my apparatus and the same raw materials, carbon black varying inproperties from those of a soft thermal decomposition vblack to those ofa hard channel 'black was produced.

While chambers varying in diameter from four and one-half inches to nineand one-half inches have been successfully used, as disclosedheretofore, I do not wish to limit my apparatus to these sizes sinceother sizes both smaller and larger may be used. For chambers. of largediameters and corresponding length, such as would be used in commerce,the optimum number and arrangement of tangential burners would need tobe determined.

Materials .of construction, as for example, preheat furnace tubes,reaction chamber insulation and lining, etc., may be selected from amongthose items commercially available and best suited to the operatingconditions as herein disclosed without departing from the scope of myinvention.

While the preferred method of operation for carry out my invention isdescribed in this specification, it. will be obvious to those skilled inthe art that there may be many possible variations of the apparatus andmethods of operation as may be vlearned from operating experience andyet remain Within the intended spirit and scope of my invention, andlimited only by the following claims.

I claim: f

1. The process of producing carbon black cornprising continuously mixinga reactant hydrocarbon gas preheated to a temperature within the rangeof l0O0 to 2400" F. and reactant air preheated to a temperature withinthe range of 1000 to 2400 F., the amount of air being insufcient forcomplete combustion of the preheated Areactant hydrocarbon gas, andcontinuously introducing this reactant mixture at approximately thecenter of the inlet end wall of an unobstructed reaction chamber havingan inlet end wall and a generally cylindrical side wall and an openoutlet end, the cross sectional area oi theI open outlet end beingsubstantially the same as the cross sectional area oi the cylindricalreaction chamber, the reactant mixture being introduced in a directionparallel to the longitudinal axis of the cylindrical chamber; burningthe gas and air to maintain the temperature in said reaction chamberbetween the limitsvof 2000 to 3300 F.; introducing a mixture of gaseousfuel and at least sucient oxygen containing gas for substantiallycomplete combustion of said gaseous fuel into the reaction chamber nearthe inlet end wall through a burner port and burning the same, saidburner port being so positioned as to direct the flow of said gaseousfuel and oxygen containing gas in a direction tangent to the innersurface of the chamber side wall and essentially perpendicular to thelongitudinal axis of saidcylindrical reaction chamber, the mixture ofgaseous fuel and oxygen containing gas being introduced through saidburner port at a sufficiently high velocity and ln sufficient quantityas to maintain the flame and combustion products by centrifugal forceadjacent the whole inner surface of the chamber side wall thus forming aseparating layer of said ame and combustion products between the sidewall and the reactant gas mixture in the reaction chamber, cooling theeiuents of the reaction chamber to below the carbon black formingtemperature and separating the carbon black from the products ofcombustion.

2. The process of producing carbon black comprising continuously mixinga reactant natural gas preheated to approximately 2000 F. and reactantair preheated to approximately 2000 F., the amount of air beinginsufhcient for complete combustion of the preheated reactant naturalgas, and continuously introducing this reactant mixture at approximatelythe center of the inlet end wall of an unobstructedy reaction lchamberhaving an inet end wall and a generally cylindrical side wall and anopen outlet end, the cross sectional area of the open outlet end beingsubstantially the same as the cross sectional varea of the cylindricalreaction chamber. the reactant mixture being introduced in a directionparallel to the longitudinal axis of the said cylindrical reactionchamber and at such a velocity that the retention time of the `saidreactantl mixture in the reaction chamber is less than 1 second; bui-ingthe gas and air to maintain the temperature in said reaction chamberbetween the limits of 2000" to 3300 F.; introducing a mixture of gaseousfuel and at least sufcient oxygen containing gas for substantiallycomplete combustion of said gaseous fuel into the reaction chamber nearthe inlet end wall through a burner port and burning the same,

said burner port being so positioned as to direct the flow of saidgaseous fuel and oxygen containing gas in a direction-tangent to theinner surface of the chamber side wall and essentially perpendicular tothe longitudinal axis of said cylindrical reaction chamber, the mixtureof gaseous fuel and oxygen containing gas being introduced through saidburner port at a sufficiently high velocity and in sufficient quantityas to maintain the flame and combustion products by centrifugal forceadjacent the inner surface of the whole chamber side wall thus forming aseparating layer of said flame and combustion products between the sidewall and the reactant gas mixture in the reaction chamber, cooling theeffluents ofthe reaction chamber to below the carbon black formingtemperature and separating the carbon black from the products ofcombustion.

3. The process of producing carbon black comprising continuouslyintroducing a reactant hydrocarbon gas preheated to a temperature Withinthe range of 1000 F. to 2400 F. at approximately the center of the inletend wall of an unobstructed reaction chamber having an inlet end walland a generally cylindrical side wall and an open outlet end, the crosssectional area ci the open outlet end being substantially the same asthe cross sectional area of the cylindrical reaction chamber, thereactant hydrocarbon gas being introduced in a direction parallel to thelongitudinal axis of the cylindrical chamber; introducing a mixture ofgaseous fuel and at least sufficient oxygen containing gas forsubstantially complete combustion of said gaseous fuel into the reactionchamber near the inlet end wall through a burner port, said burner portbeing so positioned as to direct the flow of said gaseous fuel andoxygen containing gas in a direction tangent to the inner surface of thechamber side wall and essentially perpendicular to the longitudinal axisof said cylindrical reaction chamber, burning the mixture of gaseousfuel and oxygen to maintain the temperature in said reaction chamberbetween the limits of 2000 and 3300o F. the mixture of gaseous fuel andoxygen containing gas being introduced through said burner port at asufficiently high velocity and in suicient quantity as to maintain theflame and combustion products by centrifugal force adjacent the innersurface of the whole chamber side wall thus forming a separating layerof said flame and combustion products between the side wall and thereactant gas mixture in the reaction chamber, cooling the eiiluents ofthe reaction chamber to below the carbon black forming temperature andseparating the carbon black from the products of combustion.

4. The process of producing carbon black comprising continuously mixinga reactant hydrocarbon gas preheated to a temperature within the rangeof 1000" to 2400" F. and reactant air preheated to a temperature withinthe range of 1000 to 2400D F., the amount of air being insufficient forcomplete combustion of the preheated reactant hydrocarbon gas, andcontinuously introducing this reactant mixture at approximately thecenter of the inlet end wall of an unobstructed reaction chamber havingan inlet end wall and a generally cylindrical side wall and an openoutlet end, the Acrosssectional area of the open outlet end beingsubstantially the same as the cross sectional area of the cylin dricalreaction chamber, the reactant mixture being introduced in a directionparallel to the longitudinal axis of the cylindrical chamber; burningthe gas andl airto maintain the temperature in said reaction chamberbetween the limits of 2000" to 3300 F.; introducing an oxygen containinggas at least in amount sufficient to prevent carbon deposition upon saidside wall into the reaction chamber near the inlet end wall through aburner port, said burner port being so positioned as to direct the flowof said oxygen containing gas in a direction tangent to the innersurface'of the chamber side wall and essentially perpendicular to thelongitudinal axis of said cylindrical reaction chamber, the oxygencontaining gas being introduced through said burner port at asufnciently high velocity and in sufficient quantity as to maintain atleast a por tion of the said oxygen containing gas by centrifugal forceadjacent the inner surface of the whole chamber side wall thus forming aseparating layer of said oxygen containing gas between the side wall andthe reactant gas mixture in the reaction chamberr` cooling the effluentsof the reaction chamber to below the carbon black forming temperatureand separating the carbon black from the products of combustion.

aardgas .a burner port, said burner port being so positioned as todirect the flow of said oxygen-containing gas in a direction tangent tothe inner surface of the side wall and with the predominating componentof motion perpendicular to the longitudinal axis of said cylindricalchamber,

-burning the resultingmixture of reactant hydrocarbon andoxygen-containing gas to maintain the temperature of the reactionchamber at the carbon black forming temperature, the oxygen-containinggas being introduced through said burner port at a sufficiently highvelocity and in suicient quantity as to maintain by centrifugal forcethe flame andl combustion products produced by the oxygen-containing gasadjacent the whole inner surface of the chamber side wall, thus forminga separating layer of said flame and combustion products between theside wall and the reactant mixture in the reaction chamber, cooling theeflluents of the reaction chamber to below the carbon black formingtemperature and separating the carbon black from the products ofcombustion.

6. The process of producing carbon black comprising continuouslyintroducing reactant hydrocarbons in the gaseous condition atapproximately the center of the inlet end wall of an unobstructedreaction chamber having an inlet end wall and a generally cylindricalside wall and an open outlet end, the cross section area of the openoutlet end being substantially the same as the cross sectional area ofthe cylindrical reaction chamber. the reactant hydrocarbon beingintroduced in a direction parallel to the longitudinal axis of thecylindrical chamber; introducingroxygen-containing gas nearthe inlet endwall through a burner port, said burner port being so positioned as todirect the flow of said oxygen-containing gas in the direction tangentto the inner surface ofv the chamber side wall and essentiallyperpendicular to the longitudinal axis o1 said cylindrical reactionchamber, said oxygen-containing gas and a portion of the reactant gasmixing to form a combustible mixture burning the combustible mixture tomaintain the temperature of the reaction chamber at the carbon blackforming temperature, the oxygencontaining gas being introduced throughsaid burner port at a sufciently high velocity and in sufficientquantity to maintain the llame and combustion products by centrifugalforce adjacent the whole inner surface of the chamber side wall, thusforming a separating layer of said ame and combustion products betweenthe side wall and the reactant gas mixture in the reaction chamber;cooling the effluents of the reaction chamber to below the carbon blackforming temperature and separating the carbon black from the products ofcombustion.

7. The process of producing carbon black comprising continuouslyintroducing a stream of gaseous hydrocarbon through the inlet end wallof an unobstructed reaction chamber having an inlet end wall, a sidewall having a generally cirt cular transverse cross section and an openoutlet end, the cross sectional area of the open outlet end beingsubstantially the same as the cross sectional area of the reactionchamber at this point, the reactant hydrocarbon being introduced in adirection parallel to the longitudinal axis of the chamber; introducingsulclent oxygen containing gas near the inlet end wall through a burnerport, said burner port being so positioned as to direct the flow of saidoxygencontaining gas in a direction tangent to the inner surface of thechamber side wall and essentially perpendicular to. the longitudinalaxis of said reaction chamber, said oxygen-containing gas and a portionof the reactant gas mixing to form a combustible mixture, burning thecombustion mixture to maintain the temperature of the reaction chamberat the carbon black forming temperature, the oxygen-containing gas beingintroduced through said burner port at a sufficiently high velocity andin sucient quantity to maintain the flame and combustion products bycentrifugal force adjacent the Whole inner surface of the chamber sidewall,l thus forming a separating layer of said llame and combustionproducts between the side wall and the reactant hydrocarbon in thereaction chamber, cooling the effluents of the reaction chamber to belowthe carbon black forming temperature and separating the carbon blackfrom the products of combustion.

8. 'Ihe process of producing carbon black comprising continuouslyintroducing a stream of gaseous reactant hydrocarbon at approximatelythe center of the inlet end wall of an unobstructed reaction chamberhaving an inlet end wall and a generally cylindrical side wall and anopen outlet end the cross sectional area of the open outlet end beingsubstantially the same as the cross sectional area of the cylindricalreaction chamber, the reactant hydrocarbon being introduced in adirection parallel to the longitudinal axis of the cylindrical chamber,introducing a mixture of gaseous fuel and at least sufcientoxygen-containing gas for substantially complete combustion of saidgaseous fuel into the reaction chamber near the inlet end wall through aburner port, said burner port being so positioned in the side wall ofthe cylindrical chamber as to direct the ow of said gaseous fuel inoxygen-containing gas in a direction tangent to the inner surface of thechamber side wall and essentially perpendicular to the longitudinal axisof the lsaid cylindrical reaction chamber, burning the mixture ofgaseous fuel and oxygen-containing gas to maintain the temperature ofthe reaction chamber at the carbon black forming temperature, themixture of gaseous fuel in oxygen-containing gas being introducedthrough said burner port at a sufficiently high velocity and insufficient quantity to maintain the flame and combustion products bycentrifugal force adjacent the whole inner surface of the chamber sidewall, thus forming a separate layer of said flame and combustionproducts between the side wall and the reactant hydrocarbon in thereaction chamber, cooling the effluents of the reaction chamber to belowthe carbon black forming temperature and separating the carbon blackfrom the products of combustion.

JOSEPH C. KREJCI.

